This application claims priority from Korean Patent Application No. 2003-7157, filed on Feb. 5, 2003, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference in its entirety.
1. Field of the Invention
The present invention relates to an apparatus and method for producing a semiconductor device, and more particularly, to an apparatus and method for producing a semiconductor device including a system capable of controlling certain byproducts formed during the semiconductor production process.
2. Description of the Related Art
In the chemical vapor deposition process (CVD) employed in semiconductor device fabrication, various reaction gases are used according to the reaction condition and the types of treatment gases.
Accordingly, various byproducts are formed by chemical reaction of these reaction gases some of which are undesirable. For example, when NH3 and dichlorosilane (DCS) are the gases that react with each other in a reaction chamber, at a relatively high temperature of 650° C. or more and a pressure of 10−2 torr, a desired silicon nitride film (Si3N4) is deposited.
However, at the same time, ammonium chloride (NH4Cl) is generated as a byproduct. NH4Cl is a white, odorless, crystalline substance formed by the reaction of gaseous ammonia (NH3) and hydrochloric acid (HCl). It is mainly formed at the outlet portion of a reaction chamber or a vacuum pipe, which has a relatively low temperature.
Therefore, as the deposition process proceeds, powdery NH4Cl is accumulated at the outlet portion of the reaction chamber or the vacuum pipe. As the deposition process continues, the outlet portion of the reaction chamber and the vacuum pipe become clogged.
As a result, the accumulated NH4Cl flows backward into the reaction chamber. As the amount of the accumulated NH4Cl increases in the reaction chamber, the effective inner diameter of the outlet portion of the reaction chamber and the vacuum pipe decreases. Then, the volume of the exhaust gas changes. As a result of these differences caused by the presence of excess NH4Cl, a pressure change takes place within the reaction chamber.
Conventionally, in the deposition of a silicon nitride film, the reaction chamber and the vacuum pipe are periodically cleaned to remove the NH4Cl byproduct. However, if the use of equipment for cleaning the reaction chamber is circumvented, an increase of production loss and working expense is incurred.
In attempts to overcome this problem, there have been methods of preventing the generation of NH4Cl, channeling the generated NH4Cl toward an area away from a reaction chamber, and exhausting the generated NH4Cl through the back side of a vacuum pump.
FIGS. 1 and 2 are illustrative views of an apparatus for manufacturing a semiconductor device having a construction capable of preventing the generation of NH4Cl according to an example of the prior art. FIG. 2 is an enlarged view of the part of “A” of FIG. 1.
Referring to FIGS. 1 and 2, the deposition of a silicon nitride film is performed using DCS and NH3 in a reaction chamber 12 installed in a vertical-type reaction furnace 10. During the deposition, in order to prevent the accumulation of a NH4Cl byproduct in the outlet portion of the reaction chamber 12 and in the discharge port 14, a heating jacket 70 or a heating coil (not shown) is installed around sections in which a temperature drastically drops, i.e., the “A” part surrounding the discharge port 14, the “B” part between the discharge port 14 and a vacuum pipe 20 connected to a vacuum pump 60, and the “C” part surrounding the vacuum pipe 20.
Such a heating jacket or heating coil serves to maintain the above sections at a temperature of about 150° C. In FIG. 1, a reference numeral 16 denotes a heater for heating the reaction chamber 12 to a temperature required for the deposition and a reference numeral 50 denotes a utility box.
In a method using such a heating jacket 70, as shown in FIG. 2, an external heat is applied to the outer surfaces of the discharge port 14 and the vacuum pipe 20. Therefore, the outlet portion of the reaction chamber 12, the inner portion of the discharge port 14, and the inner portion of the vacuum pipe 20 are indirectly heated and kept warm.
As a result, NH4Cl4 can be prevented from being accumulated in the reaction chamber 12 and the discharge port 14. However, because the heating jacket 70 generates heat using a heating coil inserted in an outer insulating shell made of asbestos or a flexible synthetic silicon material, a high manufacturing cost is incurred.
In addition, various problems such as breakage of the heating coil during use and degradation due to the presence of water during the cleaning operation may occur. Therefore, an average life span of the heating jacket 70 is about a year. In addition, because overheating may cause a fire hazard, installation and management of separate fire safety equipment are required.
As a direct heating method, there is adopted a method for supplying a hot N2 gas into a discharge port of a reaction chamber to prevent the accumulation of a byproduct in a vacuum pipe. FIG. 3 is an illustrative view of an apparatus for manufacturing a semiconductor device having a construction capable of preventing the generation of NH4Cl by supplying a hot N2 gas according to another example of the prior art. In FIG. 3, the same reference numerals as in FIGS. 1 and 2 denotes the same constitutional elements.
Referring to FIG. 3, a hot N2 generator 80 as a separate heating unit is installed outside deposition equipment. When a room temperature N2 gas passes through the hot N2 generator 80, a hot N2 gas with a temperature of 50° C. or more is generated. The generated hot N2 gas is supplied into the outlet portion of the reaction chamber 12 or the discharge port 14, which has a lower temperature. According to this method, the inner portions of the vacuous reaction chamber 12 and discharge port 14 are heated by the hot N2 gas, and thus, NH4Cl is prevented from being accumulated in the reaction chamber 12 and the discharge port 14.
However, the hot N2 generator 80 is very expensive. Also, in order to separately install such a heating unit outside the deposition equipment, additional costs such as a high installation cost and working expense are required, in addition to the limitation of the available installation space.
In such conventional semiconductor device manufacturing apparatuses as described above with reference to FIGS. 1 through 3, a separate expensive unit such as a heating jacket and a hot N2 generator for heating the outlet portion of a reaction chamber, a discharge port, or a vacuum pipe is required. In addition, together with a separate space for installation of such a unit, additional cost for separate electric equipment installation and working expense are required.